Arctic waters are warmer than they have been in 2,000 years, according to a new study published in the journal Science.

To recreate past water temperatures in the Arctic’s Fram Strait, scientists looked at ocean sediment containing fossilized “foraminifera” organisms dating back 2,000 years. Only one type of foraminifera prefers very cold water, from -2 to +2ºC, while the rest prefer warmer water. They found that the warmer-water foraminifera population has risen significantly over the past 100 years. They also found the level of magnesium in their shells was much higher in the last 100 years, another indicator of warmer water temperatures. They concluded that the strait’s water has warmed 3.5 degrees Fahrenheit in the past century, with a rise of 2.5 degrees Fahrenheit from the Medieval Warm Period, a time of elevated warmth from A.D. 900 to 1,300.

“Cold seawater is critical for the formation of sea ice, which helps to cool the planet by reflecting sunlight back to space,” said Dr. Thomas Marchitto, a paleoclimatologist at the University of Colorado, Boulder, and a co-author of the study. “Sea ice also allows Arctic air temperatures to be very cold by forming an insulating blanket over the ocean. Warmer waters could lead to major sea ice loss and drastic changes for the Arctic.”

Skeptics who claim that the temperature rise in the Arctic is part of a natural cycle and not caused by greenhouse gas-induced global warming were dismissed. “On a scale of 2,000 years, it stands out dramatically as something that does not look natural,” Marchitto noted.

The Arctic, a region covering Greenland, Iceland and northern parts of Russia, Norway, Canada, Sweden and the United States, just went through its warmest decade on record. It was recently reported that in 2010, the ice sheet in Greenland melted for 50 days longer than average.

Robert Spielhagen of the Academy of Sciences, Humanities and Literature in Mainz, Germany and the study’s lead author, expressed his concern. “I am afraid that my children – now 14 and 17 years old – will be able to see a summer ice-free Arctic Ocean.”

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